The present invention relates to tiltable steering column assemblies for automotive vehicles, and particularly to a lock mechanism for retaining the tilting component of the steering column in selected positions of adjustment while minimizing any lash in a steering wheel connected to the steering column.
Vehicle steering columns are often provided with a tiltable component that enables the steering wheel to be set at varying degrees of tilt, according to the desires and needs of different persons that might have occasion to drive the vehicle. Typically a manually operable lock mechanism is provided for retaining the steering wheel component in selected positions of tilt adjustment.
Representative lock mechanisms for tiltable steering columns are shown in U.S. Pat. No. 5,282,394, Dominique, et al., U.S. Pat. No. 4,463,626, Kazaoka, et al., and U.S. Pat. No. 5,222,410, Kinoshita. An advancement to the aforementioned patents is brought forth in U.S. Pat. No. 6,167,777, Snell.
The positional or tilt lock mechanism is designed to have high strength and ruggedness, while being relatively small and compact for ready installation in different size vehicles. In Snell, the positional lock mechanism has a modular construction, whereby it can be used in different types of vehicles. A special feature of the Snell lock mechanism is the use of an elongated rod between upper and lower steering column components, in combination with a locking sleeve that encircles the rod to retain the rod in selected positions of adjustment. The rod and the sleeve form an adjustable link. The sleeve is pivotally connected with the lower portion of the steering column. The rod is pivotally connected with an upper portion of the steering column. The elongation of the combination of the rod and the sleeve sets the adjustable tilt between the upper and lower portions of the steering column. The rod and sleeve have mating teeth that are discontinuous in the circumferential plane, whereby the sleeve can be rotated around the rod axis to move the teeth into or out of mesh.
The sleeve grips the external surface of the rod, such that when the teeth are in mesh, the teeth are precluded from separation, even under high impact accident conditions when high forces might be imposed on the steering column components.
One problem that may occur when the steering column is in a locked position, is lash, a state of movement in the steering wheel and column, as opposed to a solid, steady state. Lash can occur due to machine tolerances when manufacturing the specific components of the system. In premium motor vehicles it is desirable that all components have a solid feeling and that vibration or looseness of components be held to a minimum. Accordingly, it is desirable that the steering wheel conveys this solid feeling to the operator. The present invention provides a tilt adjustable steering column that eliminates or sharply reduces possible instances of lash.
The present invention provides in a preferred embodiment an articulated tiltable steering column comprising an upper steering wheel column member, a lower stationary steering column member, and a pivot connection between the upper and lower column members, whereby a steering wheel can be tiltably adjusted around the pivot connection to selected positions.
The steering column further comprises a locking mechanism for retaining the column members in selected positions. The locking mechanism is comprised of an externally threaded rod retained between the column members, and an internally threaded sleeve encircling the rod. The rod has a longitudinal axis, and has a first pivot connecting the rod to one of the column members, and a second pivot connecting the rod to the other column member. The second pivot is comprised of a pivot shaft carried by the other column member and an axial slot in the rod slidable on the pivot shaft.
The sleeve has two circumferential slots embracing the pivot shaft. The rod is comprised of a first set of circumferentially discontinuous external teeth. The sleeve is comprised of a second set of circumferentially discontinuous internal teeth. The sleeve internal teeth are in mesh with the rod external teeth when the sleeve is rotated in one direction, and the internal teeth are out of mesh with the external teeth when the sleeve is rotated in the opposite direction. The sleeve further has a tolerance cap connected thereto. The tolerance cap has a contact surface to engage the shaft and prevent relative movement of the rod with respect to the pivot shaft when the rod and the sleeve are meshed with one another.
It is a feature of the present invention to provide a tilt adjustable steering column assembly for an automotive vehicle that has minimized lash in the positional locking mechanism.
Other features of the invention will be more apparent to those skilled in the art from a review of the invention from the accompanying drawings and detailed description.